International research:
Health Council of the Netherlands, Indoor air quality in primary schools. And the value of carbon dioxide as an indicator of air quality. The Hague, 2010. (To be downloaded here).

‘Decibel’ is the crudest measure exclusively for sound volume, designated as dB(A). 35 dB(A) is the general noise standard of het World Health Organization and also of the American National Standards Institute, the so called ANSI standard, with which compliance is voluntary.

One should realize decibels don’t increase in a linear but in a logarithmic manner. An increase of 10 dB is perceived as a doubling of the noise.

Unfortunately we must stress that sound and noise is a subject the complexities of which cannot be done enough justice in this context. For instance there are ways of measuring different aspects of sound, such as ambient sound, while here we limit ourselves to crude decibels. Another limitation is that average sound levels are crude as well because they differ in time and place. In all we can only provide a limited impression of the reality of sound in different contexts.